No guarantee U.S. will have safe, effective COVID-19 vaccine, Fauci says

WASHINGTON, June 30 (Reuters) - The United States cannot count on the availability of a safe and effective COVID-19 vaccine, the government's top infectious diseases expert said on Tuesday, and he urged Americans to work together to fight the virus that is surging across large parts of the country.

California, Texas and many other states have reported record increases in new cases of the sometimes deadly illness caused by the novel coronavirus, leading to a sobering reassessment of U.S. efforts to contain the pandemic.

"It's extremely important to have safe and effective vaccines available for everyone in this country," Dr. Anthony Fauci, the head of the National Institute of Allergy and Infectious Diseases, told a U.S. Senate committee.

Fauci, however, added that "there is no guarantee ... we'll have a safe and effective vaccine," and he urged Americans to come together to contain the virus.

His remarks dovetailed with warnings by health officials that some Americans, particularly younger adults, have let down their guard since the end of mandatory lockdowns put in place in March and April to stop the pandemic.

There are fears the recent surge in cases could become turbo-charged later this week by the July 4 Independence Day celebrations, when Americans traditionally flock to beaches and campgrounds and gather to watch fireworks displays.

More than 126,000 Americans have died from COVID-19 and millions have lost their jobs. The economy contracted sharply in the first quarter and is expected to crater in the April-June period.

COVID-19 cases more than doubled in June in at least 10 U.S. states, including Texas and Florida, a Reuters tally showed.

Los Angeles, the second-largest U.S. city, has become a new epicenter in the pandemic as coronavirus cases and hospitalizations surge there despite California Governor Gavin Newsom's orders requiring bars to close and residents to wear masks in nearly all public spaces.

Los Angeles County reported nearly 3,000 new cases on Monday.

The setback has dimmed hopes that the worst of the human and economic pain had passed for the country and renewed criticism of President Donald Trump's handling of the crisis less than five months before he seeks re-election.

Democratic presidential candidate Joe Biden later on Tuesday will launch a fresh attack on Trump's "historic mismanagement" of the pandemic, said an aide who previewed his speech and who spoke on condition of anonymity.

Biden will argue that earlier action by Trump would have reduced the number who fell ill and the economic impact of the virus.

Extraordinary measures have been taken to brace the economy, with Congress allocating nearly $3 trillion in aid to businesses and individuals and the Federal Reserve slashing interest rates, ramping up bond purchases and unveiling programs to backstop and extend corporate credit and promote lending.

Fed Chair Jerome Powell and U.S. Treasury Secretary Steven Mnuchin are expected to be grilled about the effectiveness of the relief effort when they testify before a U.S. House of Representatives committee later on Tuesday.

(Reporting by Carl O'Donnell, Trevor Hunnicutt and Simon Lewis Writing by Paul Simao; Editing by Byll Berkrot)